4.3.12 Natural Selection

Question 1

What do selection pressures do

Answer 1

Increase the chance of individuals with better alleles to pass on these alleles to future generations

Question 2

Wat is the fitness of an organism defined as

Answer 2

The ability of the organism to survive and pass on its alleles to its offspring

Question 3

How does the size of a gene pool affect a species’ ability to adapt?

Answer 3

• Larger the gene pool (larger the variation)
• The more likely it is to adapt
• Less vulnerable they are to extinction
• Environmental change can severely impact them

Question 4

What causes natural selection

Answer 4

• Random mutations produce new alleles of a gene
• May benefit organism
• Better adapted to its environment
• Over several generations the new allele increases in frequency

Question 5

Typical natural selection exam question template answer

Answer 5

1. Within a species, there is always variation and chance mutation
2. Some individuals will develop a phenotype which gives them a survival advantage (eg. They can live longer, breed more, be more likely to pass their alleles onto offspring generations)
3. Repeated over many generations, the alleles become more frequent, the mutated phenotype dominates
4. If genetic differences accumulate and the population is isolated, a new species may evolve